This invention relates to an integrated article bearing indicia and, more specifically, to an integrated article including a metallic plate having thereon indicia such as letters, figures, a patterns or the like which is integrally covered with a transparent hard material, and a manufacturing process thereof.
A metallic plate having thereon any desired indicia of letters, figures, patterns or the like, applied by printing, embossing or the like has been hitherto used for a number plate for a motorcar, an advertising indication plate or the like. Such a plate is usually comparatively small in thickness, so that it is liable to be bent in use.
From the viewpoint of increasing an ornamental effect of such an article, it can be considered to form by an insertion molding or the like two covering molded plates of transparent hard synthetic resin such as silicon resin, acrylic resin or the like which are then integrally fixed to both surfaces of the metallic plate bearing the indicia.
This integrated article, however, is defective in that when it is subjected to a temperature change (-40.degree. C.-+80.degree. C.) in a natural environment, due to the fact that there is a remarkable difference in thermal expansion coefficient between the internal metallic plate and the hard synthetic resin molded plate or plates combined integrally therewith, and that each synthetic resin molded plate is a hard one, a peel-off can occur between the two, and the hard synthetic resin molded plate can crack as a result of repeated expansion and contraction of two.
The thermal expansion coefficients of various kinds of materials may be compared as listed below:
______________________________________ Iron 0.11 .times. 10.sup.-4 Steel 0.17 .times. 10.sup.-4 Aluminum 0.23 .times. 10.sup.-4 Polycarbonate resin 0.6-0.7 .times. 10.sup.-4 Acrylic resin 0.7-0.8 .times. 10.sup.-4 ABS resin 0.8 .times. 10.sup.-4 ______________________________________